These threads always crack me up, with some folks insisting other folks "prove" something all the while ignoring the actual reason folks are here (i.e., how things sound). Every network engineer suddenly also becomes an expert in psychoacoustics. Like actual listening threatens their worldview, the Luddites of the scientific community.
In my experience, the sonic difference (and what's good or bad) is largely system-dependent and also dependent on the end sound each listener is looking for (newsflash, not everyone wants neutral).
In my systems I have tried the Uptone Audio Ether Regen, the SOTM Switch (with the reclocker), the English Electric switch, and the Ansuz X-TC. All of them made an audible difference, some more than others. Honestly, if someone pops the Ansuz into their rig and they can't hear a difference they are either deaf or their system lacks the resolution to hear it. It's that simple. More clarity, a wider soundstage, and tighter more detailed bass. It's not subtle in the least. Same with the EtherRegen, but in a whole different way. That's the classic, more relaxed, less harsh sound. I came in not expecting much and was really surprised at what I heard. I tested all of these switches in both of my main rigs and while my preference for which switch worked best in each rig was different, the fact that each switch made a difference in both rigs was impossible to ignore. If you can't handle people using actual experience and trusting their own ears I suggest heading over to ASR and genuflecting at the foot of Amir. You will love it over there, trust me.
Equipment used to test--Fleetwood DeVille SQs, Volti Rival SEs, Backert Labs Rythem 1.3, McGary SA1E, Merason DAC1 MkII, Technics SU-R1000, Innuos Zenith MkIII, Innuos Pulse, Sonore Optical Rendu & Deluxe Optical Module, HiFi Rose RS130 using both ethernet and optical connections, Border Patrol SE-i DAC, Linear Tube Audio power supplies.